Delhi air pollution hits hazardous levels, but it's not the capital's problem alone

It’s November, again, and the same headlines blanket news outlets in India and the world: air pollution in Delhi has hit dangerous levels. Since last winter, this problem had faded from public concern as had the smog itself — until now. Yet, particulate pollution isn’t restricted to Delhi or to winters.

Here are the three common myths that inhibit air pollution from being front and centre of a national public health discourse, all year-long.

Myth 1: Delhi gets foggy. There is no need to be concerned In December 1952, London was engulfed in dense smog that lasted five days. Smogs were not uncommon in London, and health officials did not immediately realise the gravity of the situation. Not until the casualty rates exploded. Recent research puts the count at 12,000 premature deaths during and within two months of the Great Smog of London: a scale that was unprecedented, and changed the way air pollution was perceived.

Such particulate matter pollution is made up of tiny particles — the tiniest are about 30 times smaller than the width of hair — that come from vehicles, factories, biomass combustion and construction dust, among other sources. Given their size, they can penetrate deep into our lungs, leading to a large number of heart and lung diseases. The finer the particle, the greater the risk.

This particulate matter pollution is the single largest environmental health risk across the world, contributing to 4.2 million premature deaths in 2015-16. To put this in perspective, more deaths are attributed to particulate pollution than to Malaria and HIV-AIDS combined. A recent study from the Energy Policy Institute at the University of Chicago (EPIC), on the impact of prolonged exposure to particulates, finds that an additional 10 micrograms per cubic metre (10 ìg/m3) of PM10 pollution (PM10 is particulate matter 10 micrometres or less in diameter) reduces life expectancy by 0.6 years.

Using that metric, the researchers at EPIC have created the Air Quality-Life Index (AQLI), a tool for people to relate air quality levels in their cities to their health. Using the tool, anyone can find out how much longer they could live if air quality in their cities met national or global standards.

For the National Capital Territory (NCT), average life expectancy could increase by about six years, if particulate concentrations could be brought down to national standards (40 ìg/m3).

Myth 2: Air pollution is a problem only in Delhi and during winters Air pollution levels are unacceptably high in Delhi throughout the year. Between November 2016 and October 2017, both RK Puram in South Delhi and Anand Vihar in East Delhi exceeded the national daily standard (60 microgram/cubic metre for PM 2.5) 75% of the time. During winters, pollution levels become perceptibly worse as two factors converge.

One, atmospheric conditions trap pollutants closer to the surface of the earth, and reduce the rate at which they can disperse. This increases concentrations. Two, season-specific emissions, like the burning of biomass for heating and stubble burning, add to regular sources like vehicular emissions and construction dust. Fireworks during Diwali also spike pollution levels, and the effects persist for days.

While Delhi is certainly among the most polluted parts of the country, some other places in the Indo-Gangetic plain — spanning from Punjab all the way to Bihar and including populous cities like Lucknow, Agra, Patna and Kanpur — are just as polluted. In fact, using the AQLI, we find that the people of Agra could live 5 years longer if air pollution was reduced; Bareilly could live 4.7 years longer; and, Lucknow, 4.5 years — not that far off from the 6 years longer Delhi citizens could live. What is different is Delhi has many more monitors than other Indian cities, and therefore it becomes more public how polluted it is.

While Delhi certainly isn’t the only city that suffers from such extreme pollution, it could see the greatest gains from pollution control because of the density of population, along with the density of pollution. The population of NCT exceeds 15 million, meaning its aggregate life expectancy could improve by more than 90 million life-years if particulate levels met the national standards.

Myth 3: Cities meeting national standards need not worry The pollution levels Mumbai and Kolkata just about exceed the national standards; Bengaluru and Chennai are within national limits. How safe are their residents? Unfortunately, there is no known safe level for particulate pollution, as health effects have been detected at low levels too.

As a result, if we target improving our air quality levels to WHO standards (10 ìg/m3 of PM 2.5), a large but somewhat less polluted city like Mumbai would show a similar improvement in aggregate life years (33.2 million) saved as a smaller but more polluted city like Agra (32.6 million).

The AQLI reveals that if India reduced its air pollution to comply with the WHO’s standard, people could live about 4 years longer on average, or a combined more than 4.7 billion life years. The path to achieve this may seem daunting. But there is a long history of countries — US, Britain and Japan — that drastically improved air quality while growing their economies. We could be next.

(The writer is associate director, research, Energy Policy Institute at the University of Chicago — India. Opinions are personal)

(Disclaimer: The opinions expressed in this column are that of the writer. The facts and opinions expressed here do not reflect the views of www.economictimes.com.)